Extrusion die for the melt extrusion of flat film or sheeting

摘要

1,013,952. Die for melt-extruding flat films and sheets. UNION CARBIDE CORPORATION. Nov. 12, 1963, No. 44537/63. Headings B5A and B5B. A flat film and sheet-forming melt extrusion die includes a unitary die body 1 shown in Fig. 1 which is an end view in elevation and partially in section of the die, at the feed end thereof. Fig. 2 is an end view in elevation and partially in section of the die, at the end opposite the feed end, with the lower die lip member removed. Fig. 3 is a section taken along line 3-3 of Fig. 1. The die body 1 has a feed inlet 32 and a distributor channel 11 in communication with feed inlet 32 and with die orifice 2. The die at its end opposite feed inlet 32 is provided with end plate 30. The die has a removable lower die lip member 7 which extends into die body 1 and rests along its base, indicated by line 9, on the lower internal surface of die body 1 and abuts the perpendicular wall of die body 1 along line 10. It is held in contact with die body 1 by means of bolts 8. Rear bevelled wall of lip member 7 and that portion of land (l) of lip member 7, which extends from'the apex of wall 12 to the entrance of passageway 17, in conjunction with walls 15 and 16 of die body 1, define distributor channel 11, the cross-sectional area of which progressively decreases from the feed inlet 32 of the die to an extremity of the channel. Passageway 17, defined between land (l) of lower die lip member 7 and land (l1) of upper die lip member 3, is in communication with channel 11 and forms at its tip, die orifice 2. Upper die lip member 3 is attached to die body 1 by bolt assemblies 4 which are "push-pull" bolts by means of which the distance between die lip members 3 and 7 can be altered and the width of the slotshaped die orifice thereby adjusted. In the preferred embodiment shown in Fig. 4 the upper die lip member 44 is an integral part of die body 40 and extends under and is spaced from rigid member 43 which is also an integral part of die body 40. Members 44 and 43 are connected at intervals along their extremities by " push-pull " bolt assemblies 46 by means of which die lip member 44 is flexed at point 45 and the width of slot-shaped die orifice 41 thereby adjusted. The streamlined shape of the feed ducts in the body of the die prevent stagnation and resultant degradation of the hot thermoplastic material to be extruded and the die has the requisite strength to withstand without distortion the forces developed during the extrusion of highly viscous smelts of thermoplastics. The die can be quickly and easily cleaned.